| Contextual Infrastructure Planning and Design |
| Lighting Visualization |
| By Paul Lutkevich, Boston, Massachusetts 1-617-426-7330 lutkevich@pbworld.com
and Brian DiStasio, 1-617-960-4874, distasio@pbworld.com
|
| Getting the proper effects
from a lighting system has always been a challenge. Explaining to
your client what those effects will be and seeing if they are what
the clients want can be an ever greater challenge. The best way to
do so has always been with pictures . |
|
Lighting is often a very subjective art. Even when the designer knows
how a lighting system will interact with an environment, it often
remains difficult to explain to a client how shadowing will affect
the structural surfaces, how bright the system will appear, or how
one area will look relative to another. Even if the effects could
be explained completely, other people might not be able to fully visualize
the end product and know whether it is in line with their expectations.
In the past, we built physical models of structures and sites to see
how the lighting will look in context. These models were often incomplete
and lacked the ability to fully illustrate both the visual and luminous
design intent. We are now working with computer generated lighting
models that are proving to be great presentation tools and a powerful
and critical part of the design process.
The Process
Most project models we are working on, whether an interior or exterior,
are at least partially built in 3D. This type of modeling is becoming
the norm now that we have new design software that facilitates the
construction of these virtual project environments. It is a natural
extension to integrate the lighting design into these models.
Using 3D AutoCAD files and a visualization software called "Lightscape,"
we are performing this integration with promising results. Lightscape
allows fixture specific photometric files to be added to a CAD model,
then calculates their impact on varying surfaces and textures. Because
the entire space is calculated in the process, we are able to check
both luminance and illuminance values throughout the model, yielding
both contract required calculations and good presentation materials
(Figure 1).
Even when no 3D model exists, one can be developed relatively easily.
For example, the process to develop a roadway model begins with the
2D design files. Using Autodesk's Land Development Desktop software
(formerly known as Softdesk Civil) begin defining the horizontal and
vertical alignments. Combining the two will give you a 3D roadway
alignment. For the roadway surface generation you can utilize the
typical roadway sections, defining them as templates that, when extruded
along your 3D alignment, will place points at critical locations (roadway
centerline, edge of pavement, superelevations) in the model.
This point database is then used to create the roadway surface by
connecting the points with a network of triangulated 3-D faces. Existing
ground surfaces can be created in a similar procedure using electronic
survey point files. Combining the two surfaces will give you a 3-D
wire frame model of the project (Figure 2). Additional features such
as buildings, barriers, bridges, light poles and vehicles are created
using AutoCAD's solid modeling applications (Figure 3).
The Interior
The design of interior spaces, particularly those with significant
areas of glass, can benefit from modeling. Lightscape can provide
both the daylighting calculations that are critical to developing
appropriate energy management strategies and the nighttime calculations
when the artificial lighting is turned on (Figure 4).
Another benefit of modeling the lighting system is the ability to
readily try options. Fixture elements like lamps and colored filters
can be changed easily and evaluated visually. Custom built lighting
elements integrated into the architecture can also be evaluated. For
an underground transit station in Boston we evaluated the use of bare
fluorescent strips built into various coves and recesses of the structure.
We were able to calculate the resultant light levels and could see
the shadow patterns on elements in the station (Figure 5).
The Exterior
Exterior spaces have often been ignored when it comes to lighting
modeling and visualization. With the increased concern about light
trespass and the general public opinion that poor lighting can ruin
the nighttime visual environment, we need better means to evaluate
and represent proposed lighting designs.
We have always had numerical criteria to evaluate designs and assess
the overall performance of a system. Horizontal calculation grids
can be placed on a road or plaza to determine the adequacy of visual
performance and vertical grids can be placed along the edge of a project
to calculate the amount of light trespass. Unfortunately these numbers
are confusing to most members of community groups and seldom answer
the question of what the project will look like. Modeling of a project,
whether a road or a site, helps answer these questions for both designers
and the general public. A typical design would include images of the
project from an observer's position within the illuminated area, an
image showing relative light trespass, and a view from points of concern,
possibly an adjacent property, as illustrated in Figure 6.
Summary
Lighting visualization is a useful and powerful design tool that should
be considered for any project where lighting is an important issue
or where bad lighting can create other issues. |
|
Paul Lutkevich is a Senior Supervising Engineer
with PB's Boston office. He has 18 years of experience in lighting
and electrical design. Paul is a member of the Illuminating Engineering
Society, Commission Internationale De L'Eclairage (International Commission
on Illumination), and the Designer's Lighting Forum.
Brian DiStasio is the Lead 3D Designer for PB's Boston office. He
has more than 12 years experience in AutoCAD 3D and Softdesk. Brian
has worked on small to large scale interior and exterior models, some
as large as a square kilometer. |
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